In the art of well drilling and completing operations there has been a long-standing need for apparatus which can effectively vibrate or oscillate a tubing or casing string for various purposes, including improving primary wellbore cementing operations, releasing stuck tubing or casing and other operations, such as fishing operations, gravel packing and workover operations and the like. However, several problems remain effectively unsolved with regard to the provision of vibrator apparatus which can be connected to the upper end of well tubing, including coil tubing, or casing, and impart oscillatory vibrational forces to such tubular members without damaging associated well structure and inducing vibration of the tubular member at a resonant frequency which provides for a more effective and less energy consuming operation.
Effectively isolating vibrations induced by vibrator apparatus from associated well structure supporting the vibrator apparatus has been a somewhat nettlesome problem. Moreover, ease of modifying the vibrational forces generated by the apparatus, such as changing the mass of rotating eccentric weights, for example, has also been a problem which has received little attention in prior art vibrator apparatus. There has also been a need to provide vibrator apparatus whereby the tubular member being vibrated can also be rotated while connected to the vibrator apparatus. Still further, the provision of a system which is operable to drive rotating eccentric weight shafting and also provide for operation of a hydraulic or pneumatic vibration absorbing structure has also, heretofore, not been satisfactorily addressed in the art of well tubing or casing vibrator apparatus.
Accordingly, the present invention provides improvements which address problems in the art of well tubular member vibrator apparatus and provides certain advantages in such apparatus heretofore unknown.